1. Technical Field
The present invention relates to heat sinks. More particularly, the invention relates to heat sinks with mechanisms for mounting an electronic device.
2. Related Art
Electronic devices generate heat during operation. If the heat is not properly dissipated, the electronic device may, over time, malfunction or fail. The thermal energy generated by an electronic device may also affect the operation of nearby components, particularly given the confined spaces in which many electronic devices are installed. Thus, proper thermal management can have a significant impact on the reliability and longevity of electronic devices.
The use of a heat sink is a common technique for dissipating heat generated by an electronic device. The heat sink may be placed in thermal contact with an electronic device, and typically includes fins that extend from the body of the heat sink. The fins give the heat sink a larger surface area so that a greater amount of thermal energy dissipates from the electronic device into the surrounding environment. Heat sinks are typically fabricated from materials with high thermal conductivity to efficiently transfer thermal energy from the electronic device. However, mounting an electronic device to a heat sink can be a difficult proposition.
Electronic devices are commonly mounted to heat sinks using screws or rivets. Such methods of mounting a heat sink suffer from several disadvantages. For example, valuable space above the electronic device is generally left open to provide tool clearance in case the electronic device needs to be repaired or removed. Since screw mounting is difficult to automate, mounting the electronic device can be a time consuming and costly process. Mounting costs are also increased due to component costs, not only for the screws or rivets themselves, but also for the components typically associated with such fasteners, such as nuts and washers.
Moreover, the use of screws or rivets to mount an electronic device often degrades thermal performance. If the electronic device is of the TO-3 package type, for example, a pair of mounting tabs extend from the body of the electronic device. To mount such an electronic device, one tab is fastened to the heat sink and then the other tab is secured. Attachment of the first tab to the heat sink, however, typically deforms the tab such that a portion of the electronic device is raised above the heat sink. This is also exacerbated by the bowed base typical of TO-3 packages. Even after the second tab is fastened, the deformation of the first tab may increase thermal resistance between the heat sink and the electronic device. Screws may also be subject to loosening due to vibration, which also increases thermal resistance.
Another technique for mounting an electronic device to a heat sink is the use of spring clips. For example, Ross (U.S. Pat. No. 6,587,344), Hellinga et al. (U.S. Pat. No. 5,640,304) and Meng (U.S. Pat. No. 5,587,608) each disclose the use of spring clips for clamping an electronic device to a heat sink. These designs may work well with electronic devices having a single mounting point, such as TO-220 type packaging. However, these designs are not suitable for electronic devices with two or more mounting tabs, such as TO-3 type packaging.
Therefore, a need exists for a heat sink that overcomes the aforementioned difficulties.